Urine to Fertiliser: Percarbamide Made Electrochemically
Why in the news
A study in Nature Catalysis described a new way to pull nitrogen out of urine. Urine is called “liquid gold” because it holds nitrogen, phosphorus and potassium, the main fertiliser nutrients, but separating them from wastewater has been hard.
Key facts
- Problem: pure urea is hard to extract because salts and other compounds interfere.
- Method: an electrochemical process turns urine urea into percarbamide, making use of hydrogen bonding in urea.
- Catalyst: graphitic carbon-based; it supports two routes, direct reaction of urea with hydrogen peroxide, and binding of urea to a hydroperoxyl intermediate.
- Percarbamide: releases active oxygen and is easy to separate from urine, so urea is recovered with high purity.
- The team first aimed to stabilise liquid hydrogen peroxide, then saw urea in urine itself could serve.
Background
Phosphorus was discovered in the 17th century by Hennig Brand, a German alchemist who wrongly thought urine held gold. People eat nitrogen and excrete it as urea, so recovering it would close the nitrogen cycle.
Significance
- Slow-release fertiliser: percarbamide joins urea’s nitrogen with hydrogen peroxide’s oxidising power.
- Greener urban wastewater management.
- Supports circular economy and nitrogen cycle restoration.
Exam angle
- Lead researcher: Xinjian Shi.
- Journal: Nature Catalysis.
- Element discovered by Brand: phosphorus.